In the quiet streets of Saltillo, a curious sister follows her brother, intrigued by the secretive nature of his late-night excursions. She discovers him in a dimly lit alley, his pants around his ankles, pleasuring himself to the sounds of distant laughter. Embarrassed, he quickly zips up, but not before she catches a glimpse of his throbbing erection. Back home, she can't shake the image from her mind, and soon finds herself touching herself, imagining it's his hands exploring her body. Their secret trysts become a regular occurrence, each time pushing boundaries further, until they can no longer resist the urge to fully consummate their forbidden desires.